Using oddball ESP boards with TASMOTA

Theo Arends continues to fix, improve and expand TASMOTA at a rate that, as a mere mortal, I find incredible. One of the areas which has seen a lot of activity is the list of supported modules and devices. When you connect to the web server on your device and select the configuration menu, the top item on the list is “Configure Module”. This allows you to select your specific hardware (currently, with release 5.11.1, ranging from the original ITead Sonoff Basic, all the way through to the Arilux LC06 RGB LED controller) to enable device-specific features in TASMOTA.

While there are 40-odd entries in the module list, the question is, are you out of luck if your hardware isn’t yet included? The answer, I’m glad to report, is a resounding “Heck, no!”. Theo has included a couple of devices in the list which make it relatively easy to drop TASMOTA onto pretty much anything which has an ESP8266 device on-board and have it work,not only with the basic relay switching function, but also with a whole load of other, custom goodies connected. Here’s an example.

I usually have a couple of the “Yellow Dev Boards” to hand, mainly because they’re so easy to press into service without having to jump through too many hoops. They have plenty of nice LEDs, an on-board, low quiescent current voltage regulator and an attached battery holder (making for an easy, remote sensor platform), an LDR already wired to the ADC input, all driven by an ESP12 variant (the version has varied over time).

TASMOTA doesn’t have a configuration entry for the Yellow Dev Board specifically, but because the board has an ESP12, most of the entries on the list will work to some degree or other. Okay, so why don’t we just go with the default “Sonoff Basic” then? Because the Basic only has a limited number of GPIOs available (and some of them are inverted via MOSFET drivers), it doesn’t lend itself too well to customization. You can load your own board with the Basic and successfully connect to the TASMOTA web server, but then you really need to look through the hardware available in the “Configure Modules” list and find something which is closer to your specific hardware.

If you’re using a Witty Cloud board (rather than the Yellow), for instance, you’re in luck; entry #32 in the modules list is for that specific board. If you have a Wemos D1 Mini, that’s also included at number #18. It’s worth scanning the list to see whether your specific board might have been added recently.

As you can see from the screenshots, the entries in the list aren’t sorted, so searching for an entry can be a little difficult.

As it turns out, the WeMos D1 entry is a good choice when you’re using an ESP12 series ESP8266 and this is the one I’ve chosen in the screenshot examples (the grey entry at the very top). After selecting (and saving!) this module type, you’ll find that the GPIO options are greatly expanded, compared to the Sonoff Basic.

Note that the WeMos D1 parameter list includes the WeMos pin nomenclature to the left of the GPIO names and the Sonoff default assignations to the right. This looks a little confusing at first glance, but is actually quite useful when deciding where to connect peripheral devices on your own ESP module (for instance, assigning your relay/SSR to GPIO12 and LED to GPIO13 will still leave your device working if the module type is changed back to Sonoff Basic at any time in the future).

The drop-down selection box to the right of each GPIO (currently showing “00 None”) allows you to select what function or peripheral you’d like to have assigned to that pin. Again, choosing the WeMos D1 module type enables a wide range of options for each individual GPIO (as of version 5.11.1 of TASMOTA, there are 64 different switches, buttons, LEDs, sensors, busses, relays and functions available, including some which I assume are device specific — what’s a “PZEM Tx”?? — and others which look like a future project in the making — do “IRrecv” or “BkLight” sound interesting to anyone other than me?).

So, going back to our Yellow Dev board, we have an RGB LED, as well as a bunch of boring old red LEDs across the top of the board (see the picture, above). In this particular application, we’re going to add a DS18B20 temperature sensor to GPIO5 and a small, solid-state relay (SSR) to GPIO12 (the default Sonoff relay pin). This is going to allow us to switch an incandescent light bulb on (as a low power heater) when the DS18B20 indicates that the temperature has dropped below freezing. As it’s no fun at all to do this sort of thing without blinkenlights, we’re also going to use the RGB LED to indicate freezing temperatures (blue flashes), above freezing (red flashes) and, for bonus points with those people who aren’t as colour-blind as I am, hovering around freezing point (purple flashes). We’re also going to add a button to GPIO0 which will provide the standard Sonoff/TASMOTA functions of toggle (for the relay/SSR), as well as the ESP8266 default of forcing the module into programming mode when pressed at power-on.

We’re going to use two methods to drive the LEDs; simple on/off for the green LED (because it’s the Sonoff default power LED, as the handy cross-reference in the Module Type menu, above right, shows us) and PWM drive for the red LED (GPIO14) and blue LED (GPIO15).

One point to note about the green LED is that the xref text shows it as “Led1i”. That trailing “i” indicates that, on the Sonoff, the ESP output is inverted, because theLED is actually driven via a dedicated MOSFET. On our Yellow board there’s no driver MOSFET, so we choose the non-inverting “Led1” when assigning a device to GPIO13.

GPIO14 and GPIO15 are LEDs, but because we want to vary the intensity and mix the colours (it’s that chunky, though-hole RGB LED at the top right of the Yellow board, remember), we’re going to assign types PWM1 and PWM2 to them.

The SSR is assigned type “Relay1” on the Sonoff default GPIO12 and we assign type “DS18B20” to GPIO5. The sensor assign does neat stuff, using Theo’s modified version the One Wire code to communicate on the designated pin (you must add a 4k7 resistor between the 3v3 pin and the data pin to have this work correctly and, if you’re using a sensor on long, unshielded leads, I’d recommend that you place the resistor at the outer, DS18B20 end, rather than on the GPIO end and add a 0.1µf between the DS18B20 ground and 3v3 pins).

Here’s what the module configuration panel looks like with all of those changes made:-

When you hit “Save”, the module will be restarted with your new configuration implemented. At this point it would be a good idea to go back into the main configuration menu and select “Backup Configuration” to save all of those changes to a file on your local machine.

In the second part of this post, we’ll look at some minor hacking of the Yellow board hardware to make a functional device, as well as going over the web and MQTT commands to get the peripherals working.